The time described above is known as the waves Period.
The time which it takes for a particle to complete one full cycle is known as the period. Period is normally measured in seconds. Frequency on the other hand is the number of cycles which are completed in a given period of time e.g a second. periodic time T is given by reciprocal of frequency (1/f).
Answer:
The block's mass should be 
Explanation:
Given:
Cart with mass 
From the conservation of energy before mass is added,
Where 
amplitude of spring mass system, 
spring constant
Now new mass 
is added to the system,
Here, given in question frequency is reduced to half so we can write,
Where 
frequency of system before mass is added, 
frequency of system after mass is added.
Therefore, the block's mass should be
Answer:
Friction
Explanation:
Friction is a force that slows down moving objects. If you roll a ball across a shaggy rug, you can see that there are lumps and bumps in the rug that make the ball slow down. The rubbing, or friction, between the ball and the rug is what makes the ball stop rolling. External Force is required.
When you hit a ball it collides with the bat. When you catch a ball it collides with your hand.
